The very fact that "Much of these data are unique to a time and place, and is thus irreplaceable, and many other data sets are expensive to regenerate.", makes me wonder if this could even be considered "scientific data" anymore. Since the data is unique to a time & place and irreplaceable, it would completely destroy the reproducibility aspect of the scientific process. Given that, should the lack of reproducibility mean that lost scientific data should be redefined as experimental data or hypothesis data? It also brings up the idea in my mind that scientific data has a half life since it can degrade back to hypothesis or experimental data if not properly stored.
Completely incorrect! How can you study "how X has changed over time" if you don't have data from other times? It is also impossible in many, if not most, cases to gather such historical data in the present time.